CQL--get records by id and latest timestamp

Question

I am very new to cassandra so it might sound like a newbie question. I am running cqlsh 5.0.1 | Cassandra 2.1.4 on local.

I have a table like below:

CREATE TABLE master (
id uuid,
creation timestamp,
event_type text,
name text,
PRIMARY KEY(id,creation)
);

...and the records are:

id                                   | creation                 | event_type | name
--------------------------------------+--------------------------+------------+------------------
 305abd6d-34b8-4f36-96c6-9ea0c11be952 | 2015-04-15 14:01:54-0400 |     create |            test2
 305abd6d-34b8-4f36-96c6-9ea0c11be952 | 2015-04-15 14:03:03-0400 |     update |     test2 update
 7440c51c-6441-44fb-833b-6140fbe822eb | 2015-04-15 14:01:54-0400 |     create |            test3
 7440c51c-6441-44fb-833b-6140fbe822eb | 2015-04-15 14:03:44-0400 |     update |     test3 update
 7440c51c-6441-44fb-833b-6140fbe822eb | 2015-04-15 14:04:34-0400 |     update | test3 2nd update

 bf42a120-dec1-47d8-bde2-c0d76f1c93a5 | 2015-04-15 14:01:54-0400 |     create |            test1

How can i select all the records with distinct ids and last modified timestamp. the result should be like:

305abd6d-34b8-4f36-96c6-9ea0c11be952 | 2015-04-15 14:03:03-0400 |     update |     test2 update
 7440c51c-6441-44fb-833b-6140fbe822eb | 2015-04-15 14:04:34-0400 |     update | test3 2nd update
 bf42a120-dec1-47d8-bde2-c0d76f1c93a5 | 2015-04-15 14:01:54-0400 |     create |            test1

Answer 1

Given your current structure, you won't be able to select any other columns aside from id with a DISTINCT query. You can create another query table with just id as the PK, then run a basic SELECT on that (it should always keep the last modified date)

CREATE TABLE querytable (
    id uuid,
    creation timestamp,
    event_type text,
    name text,
    PRIMARY KEY(id)
);

SELECT * from querytable --should only contain unique ID's and the last updated creation date.

You'll have to update this table as you update the master as well.